TPS63020: -

Daniel Vera

Part Number: TPS63020

Hi,

I made the typical application with Vout=3.3V. The load drain from 30 to 140mA dynamically and powered with stable voltage 3.18V provide by lab power source.

Some times the regulator fail, Vout go to ~1.4V, working alone.

One way to reproduce the fail easily is touching with the finger the feedback resistors around 2 seconds. I think that the finger produce noise and rise down 1M resistor and produce the failure.

In normal use, nobody touching, maybe exist some noise produce the same effect.

This issue could be fixed using C4 and R4 of "Improved Transient Response for 2 A Load Current" of 8.3.1 chapter in datasheet?
Something in the design?

Thanks!

over 1 year ago

0 Tao Zhang over 1 year ago

TI__Mastermind 32350 points

Hi Daniel,

Please share your shcematic and layout here.

Yes, R4 and C4 help to filter some high frequency noise,may be that why issue fixed. One question, after you remove your finger, Vout go to normal or still stay in 1.4V?

Regards

Tao

0 Daniel Vera over 1 year ago in reply to Tao Zhang

Prodigy 50 points

Hi Tao!,

Vout stay in 1.4V.

Thanks!

Regards

0 Tao Zhang over 1 year ago in reply to Daniel Vera

TI__Mastermind 32350 points

Hi Daniel,

In your layout, path of feedback is really too long. Should keep it as short as possible.

Regards

Tao

0 Daniel Vera over 1 year ago in reply to Tao Zhang

Prodigy 50 points

Hi Tao.

Ok, I'll do that.

Doing a graphical measurement in the suggested layout, feedback path length ~1.8mm, in my design is 2.3mm an 27% more big.

~.5mm of copper is the guilty?

Thanks!

Regards

0 Tao Zhang over 1 year ago in reply to Daniel Vera

TI__Mastermind 32350 points

Hi Daniel,

There is a misunderstanding. I did not mean the connection of FB Pin, but the connection between GND of R4 and GND of device.

Regards

Tao

0 Daniel Vera over 1 year ago in reply to Tao Zhang

Prodigy 50 points

Hi Tao,

OK.

Filter isn't implemented in right now version of design but I'll do to next version.

Let the prototype working 4 days, while I been in a short vacations, and at back to office still working.

Before let this test I sent PCB to the oven one more time. So maybe some bad soldering was removed. That's could be explain why when I touched my finger the regulator fail, because the bad soldering could produces a lot of transitory states.

Thanks!

Regards

0 Daniel Vera over 1 year ago in reply to Daniel Vera

Prodigy 50 points

Hi.

I'll let closer R4, of my design, to the chip too.

Thanks.

Regards

0 Tao Zhang over 1 year ago in reply to Daniel Vera

TI__Mastermind 32350 points

Hi Daniel,

Ok, wait for your update. Actually, the layout example in DS is good and mostly you can take them as ref.

Enjoy your vacation and have good days.

Many thanks for using TI's device.

Regards

Tao

Power management

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TPS63020: -